infrasound

Infrasound refers to extreme bass waves or vibrations, those
with a frequency below the audibility range of the human ear (20
Hz to 22 kHz). Even though these waves can't be heard by us, they can be
felt and have been shown to produce a range of effects in some people
including anxiety, extreme sorrow, and chills. "Loud infrasound in the range
of 0.5 to 10 Hz is sufficient to activate the vestibular, or balance system,
in the inner ear."* Psychologist
Richard
Wiseman of the University of Hertfordshire thinks that the odd
sensations that people attribute to ghosts may be
caused by infrasonic vibrations.* He is not alone.

In 1998,
Vic Tandy, experimental officer and part-time lecturer in the school of
international studies and law at Coventry University, and Dr. Tony Lawrence
of the psychology department wrote a paper called "Ghosts in the Machine"
for the Journal of the Society for Psychical Research. They cited
infrasound as the cause of apparitions seen by staff at a so-called haunted
laboratory in Warwick.

Several years earlier, Tandy was working late in the
"haunted" Warwick laboratory when he saw a gray thing coming for him. "I
felt the hairs rise on the back of my neck," he said. "It seemed to be
between me and the door, so the only thing I could do was turn and face it."*
But the thing disappeared. However, it reappeared in a different form the
next day when Tandy was doing some work on his fencing foil. "The handle
was clamped in a vice on a workbench, yet the blade started vibrating like
mad," he said. He wondered why the blade vibrated in one part of room but
not in another. The explanation, he discovered, was that infrasound was
coming from an extractor fan. "When we finally switched it off, it was as if
a huge weight was lifted," he said. "It makes me think that one of the
applications of this ongoing research could be a link between infrasound and
sick-building syndrome." When he measured the infrasound in the laboratory,
the showing was 18.98 hertz--the exact frequency at which a human eyeball
starts resonating. The sound waves made his eyeballs resonate and produced
an optical illusion: He saw a figure that didn't exist.*

Infrasonic waves can carry
over long distances and are less susceptible to disturbance or interference
than higher frequencies.

Infrasound may be produced by
wind, by some types of
earthquakes,
by ocean waves, and by such things as avalanches, volcanoes, and meteors.*Elephants have the
ability to emit infrasound that can be detected at a distance of 2 km. Even
tigers emit infrasound.*